Zygrene

Hi all - I've spent HOURS researching this topic and doing the OBD2 drive cycles and still can't figure it out. Any guidance will be much appreciated.

I recently purchased a 2005 Carrera (63k miles) with aftermarket Fabspeed cats and center exit exhaust (GT3 bumper). To pass smog, my smog tech installed a borrowed OEM cat and left off the center exit exhaust (it won't fit with the OEM cat) and told me to drive the car to clear the monitors. So I followed the complicated drive cycle twice. Here are all the monitors as shown on the Bosch scan tool:

Misfire Monitor: OK
Fuel System Monitor: OK
Comp. Component: OK
Catalyst Monitor: INC
Htd Catalyst: N/A
Evap System Monitor: OK
Sec Air System: OK
A/C Refrig Monitor: N/A
Oxygen Sens Monitor: OK
Oxygen Sens Htr: OK
EGR/VVT Sys Monitor: N/A

Interestingly, the scan tool also logged misfire codes P0300, P0301, P0303, P0305. But right now there is no CEL on the dash.

I'm not sure if the items showing N/A are causing a problem. For now, I'm assuming the only issue preventing smog is the incomplete Catalyst Monitor. How do I go about troubleshooting? I have a Durametric tool for my Cayman S that I assume I can use on the Carrera. I've seen some people say you can "force readiness" via Durametric but I'm not sure how to do this. Is it as simple as activating the Secondary Air Injection system and hoping the values are in spec, thus readying the Cat monitor?

Thanks in advance.

TheTorch

I can't speak to the mods you are doing, nor the specific codes, but seeing as you are nearby... a drive up Junipero Sera from Stanford to past the quarry and reservoir had just the right amount of mixed driving to ready all my monitors for SMOG after a battery disconnect.

Zygrene

Thanks. I'm going to go for another drive including 10 minutes on the freeway in 6th gear, keeping rpms below 3000. Supposedly this helps ready the cat monitor.

Also I saw a thread in the 996 forum saying to cold start the engine and run the AC and rear defroster for a few minutes. Worth a shot, I guess! Just one pesky cat monitor left...

Should I avoid clearing the misfire codes? There is no CEL but the logged codes are worrying me, because last time I cleared them, all the monitors got reset...

PRC928

You will have to clear the current faults before it will complete the monitor. You can not force the monitors to complete. We deal with this all the time at our shop, unfortunately....
Most likely the current misfire faults appeared after the other monitors are set. Just to confirm, you have the stock exhaust back on now, correct? If you still have a problem with the cat monitor specifically, one thing we have had good luck with is to get on the freeway (non commute time, so you won't get run over) in a place you can set the cruise for 57MPH (under 60) and drive about 15 miles, then turn around and do another 15 back.

Zygrene

So even though there is no CEL on the dash, I have to clear the faults before the last monitor will complete? Won't all the currently ready monitors will be reset the moment I clear the fault? This is becoming a chicken-and-egg scenario.

I don't have a stock exhaust unfortunately, so I'm just running the OEM cat with nothing attached at the back. My smog tech told me this wouldn't be an issue.

TheTorch

i wonder if not having anything after the cats is keeping the cats from getting to proper temp?

PRC928

From what we see, when a fault is stored it won't continue completing the monitors. The smog tech is correct about the mufflers not being a issue for the smog test but, it could have a impact on the cat monitor because the outlet temp of the cats will be lower, as TheTorch mentioned. I would try to clear the faults and start again. On the plus side, Porsches do seem to complete these pesky monitors quicker than some others. We have more headaches with BMW's.

Zygrene

That's a good point. But even if I find a stock exhaust, it won't fit on the GT3 bumper...

This is what I was afraid of. I was hoping to deal with the misfire codes AFTER the smog test (driving on expired tags right now) but looks like I'll have to clear the faults and do the drive cycle as quickly as possible before the misfire happens again. Since I have a Durametric tool, can I clear the faults and simply force the monitors to test readiness without the drive cycle?

PRC928

If it were here at the shop, that is what we would do next. Unfortunately, there is no way to force the monitors to complete.....
I assume you have paid the registration, even though you don't have the smog? At least it keeps the penalties down.

Zygrene

Yep - previous owner paid the registration fees for 2020, even though smog is incomplete. The tags are good until December this year. I just need to pass smog so the title can be transferred to my name.

What a nightmare!

TheTorch

grab a 997.1 bumper off eBay, put the full stock exhaust on. Probably worth it to keep it since SMOG can be every 2 years.

Just an idea.

https://www.ebay.com/i/293607120079

yelcab

if it were my car, I would do this. The cat monitor will not reset if there is nothing connected to the back because O2 sensor at the rear will see extra air and the cat will not get hot enough to work. When I had a problem with my 996 GT3 with the same monitor, I tried for 200 miles and it will not reset. I took it to a shop in San Carlos and they FORCED the monitor to be ready using a Porsche tool, and passed the test.

Since then, the car has never had any CEL and passed another smog test with flying colors so it was not the equipment problem. It seems Porsche can force the monitor to go ready as part of a repair procedure.

Zygrene

Interesting. A few others have claimed there is no way to force readiness, but that it's possible to force activation of the secondary air injection pump to initiate the testing procedures without driving the car.

Do you know if your shop used a Durametric tool to force the monitor to be ready? I have one - just not sure how to use it to force readiness. I guess my other option is to ask a dealer.

Alfnado

A competent tuner can force the monitors to show "ready." Evo and WRX guys do it all the time and as far as I know, CA is still not checking CVNs (this is planned for the future so it wouldn't be a permanent fix anyway). That said, it's highly illegal and most tuners won't do it. You're better off fixing this the right way. Pretty soon all the turbo guys and others not running stock tunes are in for a fun surprise when they go to smog their cars.

yelcab

They did not use a Durametric (I have one too, professional version). They have something else, likely a Porsche tool. A Porsche dealer would not want its technician to drive the customer's car for 2 hours and 100 miles to reset a monitor after a fix is in. There has got to be a way for them to set the monitor after a repair is made.